STOCKTON - A 2-year-old boy cried for his mother as she pushed him away and abandoned him at a central Stockton park Wednesday afternoon, police and witnesses said.

"He was yelling, 'Mommy! Mommy!' and she just left him," said Daisy Hernandez, a 28-year-old mother of two who took her children to the park to play. "I was like, 'Oh, my God. Did she just leave this little boy by himself?' "

Silvia Perez, 44, left her son at Caldwell Park, in the 3100 block of Allston Way near East Alpine and North Pacific avenues, about 1:40 p.m., authorities said. Police located Perez nearby a short time later and arrested her on suspicion of child abandonment. The boy was taken into protective custody and placed at Mary Graham Hall, a children's shelter in Stockton, authorities said.

Officer Joseph Silva, a spokesman for the Stockton Police Department, credited witnesses for acting quickly to help the boy.

"The witnesses did the right thing and notified police immediately so we could ensure the 2-year-old child's safety and well-being," Silva said. "He was left alone in the park next to a busy street. If he wandered off, this situation could have been even worse. Even leaving a child alone for a few minutes or a few seconds could lead to some type of bodily harm for the child."

Silva said investigators are still trying to determine why Perez left her son at the park. Hernandez said the woman claimed the child didn't belong to her.

"I said, 'This is your child,' " Hernandez said. "She said, 'How do you know this is my child? This is not my child. This could be anybody's child.' I said, 'Well, he's calling you Mommy, so obviously that's your child.' "

Hernandez said Perez pushed her son away and walked toward S-Mart Foods on East Alpine Avenue. Hernandez said she called police and tried to comfort the boy until officers arrived, giving him snacks, drinks and a toy car that belonged to her son. Officers responded to the area and spotted Perez walking out of S-Mart Foods about 1:50 p.m., Silva said.

"When the police came, they asked the little boy, 'Where's your mommy?' " Hernandez said. "He pointed to the lady in the cop car and said, 'Yeah, that's my mommy.' It was so sad. I couldn't believe it."